But the network head's harsh words were far from Hamm's only slap in the face as a young actor.

"[I lived in] L.A. for 10 years, not working, having no money and no prospects. The days were kind of great; it was the long nights staring at the ceiling waiting for the phone to ring," he remembered. "The uncertainty is always the difficult part, at least it has been for me."

"I've just become really comfortable in portraying this guy, and I'm [still] surprised by what happens ... My statement about being comfortable in Don's skin is something that Matt is, I think, finding as well," Hamm told HuffPost TV before Season 5 premiered. "I think he’s comfortable with his characters as well, and giving them room to breathe and room to do stuff."